I worked as an energy system modeller at the Frankfurt Institute for Advanced Studies (FIAS), the Karlsruhe Institute of Technology (KIT) and the briefly for the Reiner-Lemoine-Institute (RLI). My focus lies on the optimization of low-carbon energy systems. We have build a toolbox for this, Python for Power System Analysis (PyPSA), which has a special focus on grid modelling and I setup and maintain the model PyPSA-Eur for optimizing the renewable expansion of the European electricity system.